Acute Spinal Cord Injury: Correlations and Causal Relations Between Intraspinal Pressure, Spinal Cord Perfusion Pressure, Lactate-to-Pyruvate Ratio, and Limb Power

Abstract

Background/Objective: We have recently developed monitoring from the injury site in patients with acute, severe traumatic spinal cord injuries to facilitate their management in the intensive care unit. This is analogous to monitoring from the brain in patients with traumatic brain injuries. This study aims to determine whether, after traumatic spinal cord injury, fluctuations in the monitored physiological, and metabolic parameters at the injury site are causally linked to changes in limb power. Methods: This is an observational study of a cohort of adult patients with motor-incomplete spinal cord injuries, i.e., grade C American spinal injuries association Impairment Scale. A pressure probe and a microdialysis catheter were placed intradurally at the injury site. For up to a week after surgery, we monitored limb power, intraspinal pressure, spinal cord perfusion pressure, and tissue lactate-to-pyruvate ratio. We established correlations between these variables and performed Granger causality analysis. Results: Nineteen patients, aged 22-70 years, were recruited. Motor score versus intraspinal pressure had exponential decay relation (intraspinal pressure rise to 20 mmHg was associated with drop of 11 motor points, but little drop in motor points as intraspinal pressure rose further, R 2 = 0.98). Motor score versus spinal cord perfusion pressure (up to 110 mmHg) had linear relation (1.4 motor point rise/10 mmHg rise in spinal cord perfusion pressure, R 2 = 0.96). Motor score versus lactate-to-pyruvate ratio (greater than 20) also had linear relation (0.8 motor score drop/10-point rise in lactate-to-pyruvate ratio, R 2 = 0.92). Increased intraspinal pressure Granger-caused increase in lactate-to-pyruvate ratio, decrease in spinal cord perfusion, and decrease in motor score. Increased spinal cord perfusion Granger-caused decrease in lactate-to-pyruvate ratio and increase in motor score. Increased lactate-to-pyruvate ratio Granger-caused increase in intraspinal pressure, decrease in spinal cord perfusion, and decrease in motor score. Causality analysis also revealed multiple vicious cycles that amplify insults to the cord thus exacerbating cord damage. Conclusion: Monitoring intraspinal pressure, spinal cord perfusion pressure, lactate-to-pyruvate ratio, and intervening to normalize these parameters are likely to improve limb power.

Acute, severe traumatic spinal cord injury: improving urinary bladder function by optimizing spinal cord perfusion

“…In our study, transiently increasing the SCPP reduced the threshold volume for bladder sensation. The finding that SCPP ≥ 100 mm Hg worsens bladder function supports the idea that not only hypoperfusion, but also hyperperfusion, is detrimental for the injured cord; we urge caution, however, because this statement relies on Our earlier work, using limb power and sensory level as outcomes, 6,[12][13][14] and the current study of bladder function suggest that SCPP is the key parameter to monitor and optimize after acute TSCI. Some aspects of bladder function, assessed acutely, correlated with corresponding measurements at followup.…”

“…These techniques are described elsewhere. 4,6,8,[10][11][12]14,21 ISP and MD measured under the conditions of this study differ from intrathecal pressure and MD measured above or below the injury site because the injured cord is compressed against the dura, thus compartmentalizing the intrathecal space. 14,[22][23][24]…”

“…For example, intervention to increase SCPP (MAP − ISP) may be achieved using inotropes to increase MAP 6 or expansion duroplasty to reduce ISP. 30 Increasing SCPP may increase cord tissue glucose and reduce cord LPR, 12 which may improve neuronal activity at the injury site, thus leading to improved bladder function. In our study, transiently increasing the SCPP reduced the threshold volume for bladder sensation.…”

“…5,6 We monitor intraspinal pressure (ISP), spinal cord perfusion pressure (SCPP), 5-8 and cord metabolism. 9-11 ISP and SCPP are clinically important parameters that correlate with injury site metabolism, 9-11 neurological status, 6,12,13 and long-term outcome 14 and are causally linked to limb power. 12 Chronic TSCI often leads to unfavorable urodynamics defined as dangerously low bladder compliance (< 20 mL/…”

Medical Communication Services after Traumatic Spinal Cord Injury

“…Cervical, thoracic, and lumbar region that reported different procedures (durotomy and myelotomy) and the effect of these methods in achieving good or bad outcomes were studied. Monitoring ISP and SCPP provides information about prognosis and improve the neurological outcome [ 10 ]. We did not exclude studies based on patient characteristics, the timing of outcome assessment, study design, language, or publication status.…”